Watching Washington Butterflies with Bob Pyle: Number Twenty

As in the old Sam Cook song, we might not know much about biology, but we do know what we love. And we all love butterflies. And butterflies love the sun and the warmth and the full-on growth of fresh plants in the springtime. We come to expect that certain species will appear at certain times, often predicted by what’s happening in the vegetative realm. And to the extent that we can recognize these comings and goings, and correlate them with one another and the changing seasons, then perhaps we know something about phenology after all.

Phenology (from the Greek phain?, which refers to light, or appearance; and logos, having to do with knowledge) is the branch of biology that brings itself to bear upon seasonal changes in living communities. When we speak of phenological signs, we are speaking of when the first swallows appear or disappear according to their migration, when frog-song resumes in the early spring, or when the sap is right for tapping in a maple sugarbush. The flight period we associate with each species of butterfly is perhaps the key phenological fact for our purposes.

Even as I write, on this early March morning, I am distracted by the butterfly activity outside. Four species have appeared at Swede Park in Wahkiakum County today: one fresh Margined White, flying a full circuit around the house. A bright Satyr Anglewing, fluttering right outside the kitchen window as I made coffee, and cruising around the front porch all morning since; Echo Azures floating about a cherry laurel coming into bloom, and nectaring on heather; and four or five Mourning Cloaks all over the place-nectaring on the laurel, basking on logs, and flying high in twinned courtship flights. None of these species are unusual for March, but such a display this early in the month is definitely unusual here.

But this has been that kind of a winter, of a spring! For the first time in my memory, I saw skunk cabbage five inches up in a swamp even before New Years-on a frigid Christmas Bird count in late December, in fact-and things went from there. Also for the first time I can recall, the advent of the daffodils pre- ceded that of the crocuses. Daffodil leaves were six inches up before I noticed a single crocus break ground. The very first bulbs to bloom every year, the snow- drops, came out a week early, but then fizzled with just a fraction of their normal drifts. And when the daffodils finally bloomed, in early February the crocuses had almost caught up. By March, both had largely gone over, as had a pink camellia that normally doesn’t even break bud until then. As I speak, a host of pollinators- honeybees, bumblebees and several other native bees, beeflies, hover flies, and others-along with the early geometrid moths Mesoleuca gratulata and Enchoria lacteata, are all over the white spiraea flowers. The Asian pear is just busting into bloom, and there is plenty of time still for late, hard frosts, which would mean no Asian pears in August. So, no wonder all the butterflies that are distracting me out there. All this is phenology.

Not that this is the first spring things have been like this. I remember one season in the late nineties when the Pacific chorus frogs actually bore a second generation over the winter in stock ponds that never froze, and their spring chorus came full-throat on the fourth of January. Then there was the spring of 2007, when I was teaching in Montana and harbored immense envy for all the lepists back home in Cascadia who were raking in the butterfly sightings by the early bushelsful! Such a spring as the current one is not necessarily a direct result, or indicator, of global warming, though it is probably much affected by the Great Warming. Because the climate and everything affecting it lie along a gradient of variability (as does almost everything else), actual cause and effect can be very difficult to pin down. There have always been warmer, colder, earlier, later seasons. What is different is that now the early, warm ones are likely to be more frequent and more extreme, at least in our mellow (if moist) corner of the continent.

What CAN be said with reliability is that an organism’s, or a community’s, or a locality’s phenology is directly and measurably concocted from and affected by a number of discrete factors. These include the fixed quantities, such as latitude, longitude, altitude, daylight, and distance from the coast or mountain ranges; and the variables, including precipitation, mean, minimum, and maximum temperatures, humidity, winds and storms, and barometric pressure. Scientists mostly concur that a butterfly’s emergence time (at least for many species) depends primarily upon a delicate dance between average temperatures and length of daylight, as modified or ameliorated by the other factors named above.

After all, if the Echo Azures or Becker’s Whites all emerged when a certain temperature was reached, and then the thermometer dropped radically again and stayed there, they’d all freeze, and a year’s reproduction might be lost. Conversely, if they all waited for a certain length of day to come out, they might have missed a month of warm days already, and find their host plants past bloom or all dried out. By averaging out both factors into a complex matrix the insects’ receptors (as honed by the harsh lessons of evolution) give the thumbs-up for all systems go when the likelihood of survival is strongest. Moisture and direct sunshine further factor in the mix. And underlying it all is genetic variability, so that not every individual responds the same to the same cues: there is a natural spread of earlier or later emergers, as genetically determined. So put the hardwired factors together with the adaptive variables, and you get a phenological spread that should be most favorable to survival for the greatest number of emergers.

So, if the elegant back-ups and redundancies and collaborative features furnished by the kindly care of evolution ensure that butterflies and weather generally work out well together, why should we be concerned about climate? If the fact that winters are generally getting warmer and shorter here, and southerly species are certainly advancing north to swell our checklist, and our butterfly season is likely to go on advancing until the field trip schedule will have to begin in January, shouldn’t we just sit back and enjoy it all and thank the gods we live where we do? Of course we should, and we do, and we shall. But that’s not the whole story. At least three downsides may attend this rosy picture.

First, even if the Pacific Northwest becomes a more salubrious location for butterflies and butterfliers, that doesn’t mean that both aren’t suffering in other locations. And while Buckeyes show up in eastern Washington and Virginia Ladies overwinter on the west side, we may be fixing to lose much rarer species (such as Melissa Arctics and Lustrous Coppers) off the tops of our northern mountains as the climate stokes up the furnace. Drying and warming elsewhere may harm the overall butterfly picture (and of course, for many other organisms), even as we enjoy earlier spring days full of butterflies, such as today. Two different articles in the Spring 2015 issue of Douglasia (WA Native Plant Society) indicate how the phenology of alpine meadow and vernal wet meadow plants will be adversely affected by diminished snowpack in the Cascades. Such changes will certainly rebound in a decline of the butterflies dependent upon these plants as well.

Secondly, another threat lies in the differing phenologies of animals and plants. No matter how well oiled the machinery governing emergence, with respect to temperature and survival, it will all come to naught if the right plants don’t come out at the right time. And the plants’ phenology is not necessarily directly linked to that of the animals that depend upon them, and vice versa. So we are already seeing instances of butterflies making their curtain-call, only to find key vegetative cast members absent. This cuts both ways: not only will the insects find a lack of floral resources, but when the flowers finally pop (or pop even earlier) they might not find their pollinators waiting for them. In one example, northbound Monarchs have returned from Mexico much earlier than usual lately, when southland springs have come hot and dry. When this happens, and the effect is exacerbated by those hot and arid conditions, the new growth of milk- weed is not yet ready or sufficient for the egg load the Monarchs would like to leave behind. You can see how such asynchronous match-ups-basically, stood-up dates-don’t go down very well. This liability of climate change affecting plants and co-evolved animals differentially to their mutual disadvantage is called phenological displacement. We’ll see more and more of it. The question is, can the affected plants and animals co-adapt again, and rapidly enough to recalibrate their dance? That’s hard to do, when the climate is a moving target.

And the third problem? How am I supposed to get this column written, with all the butterfly action outside? If our butterfly springs go on like this, we’re all in trouble!

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